Form and function intersect

Aurecon engineer Tony Lavorato played a lead role in the design of Sydney’s award-winning 5 Martin Place project. Liberty OneSteel talked with him about the unique challenges of the project and why adaptability is key to building designs of the future.

Tony Lavorato has made a specialty of hatching design solutions to overcome challenging project constraints.

Of the many developments he has worked on over the course of a three-decade-long engineering career, he describes Sydney’s 5 Martin Place building as one of the most complicated. As lead structural engineer on the Grocon project, which ran from 2011 to 2015, Lavorato faced dealing with the tight confines of the building’s CBD location, a restricted construction zone and building height limitations, not to mention the very substantial challenges associated with constructing a new building over an existing heritage edifice.

With endeavour comes reward and Lavorato now counts 5 Martin Place as one of the most satisfying redevelopment projects he has worked on. The building has also received generous critical acclaim, winning the Australian Steel Institute Award for Steel Excellence in Buildings – Large Projects in 2016, an Award for Heritage and for Commercial Architecture at the 2016 National Architecture Awards and, most recently, the RLB Australian Development of the Year for 2017.

“The project is by far the most complex in terms of engineering gymnastics of any building I’ve ever been involved in,” Lavorato says. “My desire is to stop everyone in Martin Place and make them look up and to tell them about it. What lies behind this sympathetic addition to an existing building is a world-first structural solution.”

Making the most of place

Lavorato applies his knowledge and skills as Design Director at Aurecon not just towards devising design solutions for a variety of structures, but towards ensuring concepts are addressed accurately in the early stage of a project and ensuring consistency of design across projects. As well as tackling complex structural underpinnings, he counts his specialties as conceptual structural design, and analysis and design of multi-storey buildings.

His calling has led him to roles in Asia and the Middle East, but he has spent the bulk of his professional career in Sydney. He says Australia’s largest city is blessed as much for the quality of its foundations as it is for its natural beauty above ground.

“Sydney is very fortunate because it has very good geotechnical conditions,” Lavorato says.” As opposed to other major Australian capital cities that were built on rivers, Sydney is built on a drowned valley. That means the rock is very close to the surface, thus giving builders the ability to construct significant buildings and utilise basements under them.”

He says today’s engineers have their work cut out for them finding a piece of Sydney land that doesn’t already have a building of note on it – or finding a way to maximise use of prime city real estate.

“It’s a fact now that there are no easy building sites left in the city of Sydney,” he says. “If there’s not a substantial building on the site now, there’s a good reason for it – there’s a tunnel under it or there’s a restriction of some kind associated with it.

“Perhaps constructing a certain building on that site wasn’t commercially viable previously, but the returns that developers are getting on those sites now makes what was previously not viable now viable.

“But only with the input of some good engineering to overcome the constraints of the site,” he adds.

A faithful interpretation

The 5 Martin Place project certainly met the criteria of a site with immense commercial and cultural significance, but sorely in need of a novel approach to help maximise its potential.

Of all the challenges associated with restoring 5 Martin Place, the key one was this: how best to rejuvenate a century-old building and extend its net lettable area while also retaining its distinctive historic character?

Constructed in 1916 to house the headquarters of the Commonwealth Bank of Australia, the ‘Money Box’ building as it came to be known was one of the first in the world to use a structural steel frame. It set new standards at the time for a commercial office building in Sydney and was notable for its use of natural light and ventilation. Extensions were added to the building in 1930 and then again in 1968.

For the most recent ‘fourth phase’ of the building’s development, architects Johnson Pilton Walker and Tanner Kibble Denton devised plans to deliver the additional floor space needed to make it a commercially viable proposition. With Lavorato as Principal Structural Engineer, and working closely with builder Grocon, the design team arrived at an innovative steel-framed solution that involved demolishing the 1968 structure and replacing it with a new 20-storey building, part of which (levels 11–20) was to be cantilevered over the existing heritage building.

Lavorato’s contribution was to prove that a set of splayed columns forming V-shaped braces on all four sides of the building was the best method for securing the cantilevered section of the new structure. The ‘smarts’ of the building are all hidden from view, he says. It’s a concept that he says goes back to simple engineering theory, although its execution involved the creation of complex and distinctive load paths.

“The floorplate in the new building has very few internal columns so we utilised long-span large panels and had to take dynamic load very heavily into consideration,” he says. OneSteel supplied a range of beams from 360UB to 610UB sections to enable the new building’s significant spans.

Lavorato’s approach involved reducing the number of steel members and altering their type. The major compression elements were changed to concrete-filled steel tubes, which allowed the concrete to resist about 80 per cent of the load, while still retaining the erection advantages of steel. The major tension elements were constructed using post-tensioned concrete. The solution meant that approximately 450 tonnes of steel were saved.

5 Martin Place is now a light-filled Premium Grade building offering 33,860 sqm of NLA and a full complement of tenants across 20 levels.

Significantly, the redeveloped site offers proof that contemporary thinking can co-exist with heritage grandeur. The original Commonwealth Bank building has been rejuvenated to a high standard while still retaining its historic features, such as its impressive sandstone facades, soaring ceiling heights and a majestic lobby with marble flooring. Light streams into the core of the heritage floors through the atrium much as the architects of the original building intended.

An eye on the future

Lavorato says we need to remember where we’ve come from as we hurtle towards the future – and that the imprint of history on a building is something to be preserved and celebrated, much as it has been with 5 Martin Place. It’s no surprise he derives inspiration for his work from ancient forms found around the world.

“When you look at a structure that was made centuries ago and you consider that it was built without any of the analytical tools we’re accustomed to using, it’s hard not to be inspired by its form and how it works,” he says.

The idea that buildings can make a significant contribution to the social fabric of a city is something Lavorato says has increasingly motivated him as his career has progressed. The concept of ‘place-making’ has inspired his work on a number of significant public buildings throughout Sydney such as schools, universities and housing.

Lavorato sees steel as making an important contribution to the urban renewal process right around the world. Steel’s main advantage is – and will continue to be – its flexibility, he says.

“Structural steel can provide fantastic flexibility in the way it can be transformed, allowing designers the ability to adapt flooring to put in additional stairs or introducing voids, for example. Another very real advantage of steel is that it allows us to disassemble buildings in which steel is used so that it can be repurposed.”

He nominates London’s Leadenhall Building as a recently built structure that has impressed him for its adaptability. “The driver for it was to reduce the amount of poured concrete used, so it has ended up using structural steel in a really innovative way.”

The need for flexibility in how we conceive of our built environment is something Lavorato expects will continue to influence our approach to building design.

“Think of the way we work now. The big driver now is to have fewer closed office space, so we’re pulling floors out, installing atriums and putting in interconnecting stairs in older buildings,” he says.

“We don’t know how we’ll work in 10–15 years, but if we can produce a design that’s adaptable – and steel certainly lends itself to that – we can ensure our buildings satisfy our demands well into the future.”